1. Field of the Invention
The present invention relates to a thermochromic window doped with a dopant and a method of manufacturing the same, and more particularly, to a thermochromic window doped with a dopant and a method of manufacturing the same, in which the thermochromic window has a low phase transition temperature.
2. Description of Related Art
In response to soaring prices of chemical energy sources such as petroleum, the necessity for the development of new energy sources is increasing. In addition, the importance of energy saving technologies is increasing with the necessity for new energy sources. In fact, at least 60% of energy consumption in common houses is attributed to heating and/or cooling. In particular, common houses and buildings lose up to 24% of their energy through windows.
Accordingly, a variety of attempts have been made in order to reduce the amount of energy that is lost through windows by increasing the airtightness and insulation characteristics thereof while maintaining the aesthetics and the characteristics of view, which are the basic functions of windows. Representative methods, by way of example, include varying the size of the windows and furnishing high-insulation windows.
Types of high insulation window glass include an argon (Ar) injected pair-glass, in which Ar gas or the like is disposed between a pair of glass panes in order to prevent heat exchange, a low-e glass, and the like. Also being studied is a type of glass that is coated with a layer that has specific thermal characteristics in order to adjust the amount of solar energy that is introduced.
In particular, the low-e glass is coated, on the surface thereof, with a thin layer of metal or metal oxide, which allows most visible light that is incident on the window to enter, so that the interior of a room can be kept bright, while radiation in the infrared (IR) range can be blocked. The effects of this glass are that it prevents the heat of heating from leaking to the outside, and also prevents the energy of heat outside a building from entering, thereby reducing cooling and heating bills. However, this window has the following drawbacks due to its characteristic of reflecting wavelengths other than visible light. Specifically, it does not admit the IR range of sunlight into the interior of a room, which is a drawback, especially in winter, and the sunlight transmittance thereof is not adjusted according to the season and/or temperature.
Accordingly, the development of technologies for thermochromic windows which are provided by coating a glass with a thermochromic material is underway. Such a thermochromic window blocks near infrared (NIR) radiation and infrared (IR) radiation while allowing visible light to pass through when the glass arrives at a predetermined temperature or higher, thereby preventing room temperature from rising.
FIG. 1 is a graph showing variations in the level of sunlight transmittance of a thermochromic window before and after the phase transition, in which one surface of a glass substrate is coated with a thermochromic thin film made of VO2.
As shown in FIG. 1, it can be appreciated that, when the glass is coated with the thermochromic material, the transmittance of the glass for solar light, in particular, in an IR range differs before and after phase transition. This can consequently improve the energy efficiency when cooling and heating a building.
However, it is difficult to put thermochromic materials into practice in actual construction glass, since they have a high phase transition temperature. In particular, even the phase transition temperature of vanadium dioxide (VO2) which is relatively close to the practically available temperature is 68° C.
Accordingly, a thermochromic thin film made of a thermochromic material is doped with a dopant in order to lower the phase transition temperature of the thermochromic thin film.
Doping methods of the related art include a method of co-sputtering a target made of a thermochromic material and a target made of a dopant and a method of sputtering a thermochromic material using a target that is doped with a dopant.
However, these methods have a problem in that the dopant is uniformly dispersed and distributed across the entire area of the thermochromic thin film, thereby decreasing the level of visible light transmittance and phase transition efficiency of the thermochromic thin film.
The information disclosed in the Background of the Invention section is provided only for better understanding of the background of the invention, and should not be taken as an acknowledgment or any form of suggestion that this information forms a prior art that would already be known to a person skilled in the art.